Electroactive polymer-based actuation mechanism for circular stapler

ABSTRACT

Methods and devices are provided for actuating and/or articulating a circular stapler. In one exemplary embodiment, a circular stapler is provided having an elongate shaft with a stapling apparatus coupled thereto. An electrically expandable and contractible actuator, such as an electroactive polymer actuator, can be used to pivotally or angularly adjust a position of the stapling apparatus relative to the elongate shaft by delivering energy to the electroactive polymer actuator. In another embodiment, an electroactive polymer actuator can be used to actuate the stapling apparatus, thereby driving one or more staples, preferably in a substantially curved pattern, into tissue. The actuator can alternatively or additionally drive a blade distally to cut tissue being stapled.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent applicationSer. No. 11/082,495 filed on Mar. 17, 2005 and entitled “SurgicalInstrument Incorporating an Electrically Actuated ArticulationMechanism,” which claims priority to U.S. Provisional Application No.60/591,694 filed on Jul. 28, 2004 and entitled “Surgical InstrumentIncorporating an Electrically Actuated Articulation Mechanism.” Theseapplications are hereby incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates broadly to surgical devices, and inparticular to methods and devices for articulating and/or actuating anend effector on a surgical tool, such as a circular stapler.

BACKGROUND OF THE INVENTION

Endoscopic surgical instruments are often preferred over traditionalopen surgical devices since a smaller incision tends to reduce thepost-operative recovery time and complications. Consequently,significant development has gone into a range of endoscopic surgicalinstruments that are suitable for precise placement of a distal endeffector at a desired surgical site through a cannula of a trocar. Thesedistal end effectors engage the tissue in a number of ways to achieve adiagnostic or therapeutic effect (e.g., endocutter, grasper, cutter,staplers, clip applier, access device, drug/gene therapy deliverydevice, and energy device using ultrasound, RF, laser, etc.).

Anastomosis is the surgical joining of separate tissue sections.Typically, an anastomosis procedure follows surgery in which a diseasedor defective section of hollow tissue is removed and the remaining endsections are to be joined, however hemorrhoidal or other tissue can alsobe anastomized. Depending on the desired anastomosis procedure, the endsections may be joined by either circular, end-to-end, or side-to-sideorgan reconstruction methods.

In a circular anastomosis procedure, the two ends of the tissue sectionsare joined by means of a stapling instrument which drives a circulararray of staples through each tissue section and simultaneously coresany tissue interior of the driven circular array of staples to create atubular passage. Known circular staplers typically include an anvil headthat is positioned adjacent to a staple holding component. Opposed endportions of the tissue to be stapled are clamped between the anvil headand the staple holding component, and the clamped tissue is stapled bydriving one or more staples from the staple holding component so thatthe ends of the staples pass through the tissue and are deformed by theanvil head. An annular knife can be concurrently or subsequentlyadvanced to core tissue to create a tubular passage.

One drawback to current circular stapling devices is that a large forceis required to effect firing, and the force changes throughout thecourse of the firing stroke. Most current circular stapling devicesutilize a hand-squeezed trigger. The load is low during early portionsof the stroke when the staples are advancing out of the cartridge andpiercing the tissue. Once the staples enter into the anvil pockets, theresistance and load rises rapidly as the staple legs buckle. Then theresistance and load drop down and rise again as the staples are formed.In contrast, the operator has maximum effective strength at the earlyand mid-stages of the firing stroke, whereas the effective strength isminimized during the final stages of closure. The large force necessaryto effect firing, as well as the variations in the force, can oftenexceed the surgeon's hand strength and could potentially result inbinding or other malfunctions that may occur when an unexpectedly higherforce is required.

The large force required to effect firing can also interfere with theflexibility or adjustability of the shaft. Currently, the staple holdingcomponent can be pivotally coupled to the shaft, or the shaft can beflexible to allow the shaft to travel through a curved pathway. Thetransfer of force from the handle to the staple holding component cannecessarily interfere with the pivoted or curved orientation of theshaft, potentially causing it to straighten.

Accordingly, there remains a need for methods and devices for actuatingand/or articulating a circular stapler, and in particular for methodsand devices that require a low force to effect actuation and/orarticulation of a circular stapler.

BRIEF SUMMARY OF THE INVENTION

The present invention provides various devices and methods for staplingtissue. In one embodiment, a circular stapling device is provided thatincludes an elongate shaft with a stapling apparatus coupled to thedistal end of the elongate shaft and adapted to deliver staples intotissue in a substantially curved pattern. While the stapling apparatuscan have a variety of configurations, in one embodiment the staplingapparatus includes a staple applying assembly and an anvil that iscoupled to the staple applying assembly and movable between an opentissue-receiving position and a closed staple-applying position. In anexemplary embodiment, the device also includes one or more actuators foreffecting articulation and/or actuation of the stapling apparatus. Thedevice can also include a handle that is formed on the proximal end ofthe elongate shaft and that has a control mechanism for selectivelydelivering energy to the actuator(s).

In one embodiment, actuation of the device can be achieved using anelectroactive polymer actuator that is coupled to the staple applyingassembly and that is adapted to drive one or more staples into tissuepositioned between the staple applying assembly and the anvil. Forexample, the staple applying assembly can include a driver that isadapted to move distally to drive staples through the staple applyingassembly toward the anvil. The driver can optionally have a blade formedthereon that is adapted to cut stapled tissue. The electroactive polymeractuator can be coupled to the driver and the staple applying assembly,and it can be adapted to move the driver distally when energy isdelivered to the electroactive polymer. While the electroactive polymeractuator can have a variety of configurations, in one exemplaryembodiment the electroactive polymer actuator can be in the form of oneor more electroactive polymer cords that are adapted to axially contractwhen energy is delivered thereto to pull the driver distally within thestaple applying assembly.

In another embodiment, the stapling device can include an electroactivepolymer actuator that is coupled to the anvil and that is adapted tomove the anvil from the open tissue-receiving position to the closedstaple-applying position when energy is delivered to the electroactivepolymer actuator. In an exemplary embodiment, the electroactive polymeractuator is in the form of an electroactive polymer cord that axiallycontracts when energy is delivered thereto to pull the anvil toward thestaple applying assembly.

Methods for stapling tissue are also provided. In one embodiment, themethod can include inserting a circular stapler into a lumen,positioning tissue to be stapled between an anvil and a staple applyingassembly located on a distal end of the circular stapler, and deliveringenergy to an electroactive polymer actuator coupled to the stapleapplying assembly to drive a plurality of staples through the stapleapplying assembly and against the anvil to staple the tissue positionedtherebetween with staples positioned in a substantially curved pattern.In one embodiment, delivering energy to the electroactive polymeractuator can be effective to move a driver disposed within the stapleapplying assembly to drive staples therethrough and against the anvil.In an exemplary embodiment, the electroactive polymer actuator canaxially contract when energy is delivered thereto to move the driverthrough the staple applying assembly. In another embodiment, anelectroactive polymer actuator can be coupled to the anvil and energydelivery to the electroactive polymer actuator can pull the anvil towardthe staple applying assembly.

In another embodiment, articulation of an end effector of a circularstapling device can be achieved using an electroactive polymer actuator.For example, the device can include an elongate shaft, and an endeffector movably coupled to a distal end of the elongate shaft by anarticulation joint. The end effector can be adapted to deliver staplesinto tissue in a substantially curved pattern. The device can alsoinclude an electroactive polymer actuator coupled to the articulationjoint and adapted to move the end effector about the articulation jointrelative to the elongate shaft when energy is delivered to theelectroactive polymer actuator.

While various techniques can be used to move the articulation jointusing the end effector, in one embodiment the elongate shaft can includea slide bar extending therethrough and having a distal end coupled tothe articulation joint. The electroactive polymer actuator can beconfigured to move the slide bar laterally to effect movement of the endeffector. For example, the electroactive polymer actuator can includefirst and second electroactive polymer actuators disposed on opposedsides of the slide bar. The slide bar can include gears formed on adistal end thereof and adapted to engage corresponding gears formed inthe articulation joint. In another embodiment, the articulation jointcan be in the form of a pivot joint, and the electroactive polymeractuator can include a first electroactive polymer actuator extendingbetween a first side of the end effector and a first side of theelongate shaft, and a second electroactive polymer actuator extendingbetween a second opposed side of the end effector and a second opposedside of the elongate shaft. In yet another embodiment, the articulationjoint can be in the form of a flexible portion formed between theelongate shaft and the end effector. The electroactive polymer actuatorcan include a plurality of electroactive polymer actuators coupled tothe flexible portion at distinct locations, each of the plurality ofelectroactive polymer actuators being configured to change orientationswhen energy is selectively delivered thereto to flex the flexibleportion.

A method for fastening tissue is also provided and in one embodimentincludes inserting an elongate shaft of a circular stapling device intoa body lumen to position an end effector movably coupled to a distal endof the elongate shaft adjacent to a surgical site, delivering energy toan electroactive polymer actuator to angularly position the end effectorrelative to the elongate shaft, and simultaneously advancing a pluralityof staples through the end effector to staple tissue disposed adjacentto the end effector. Delivering energy to the electroactive polymeractuator can cause the electroactive polymer actuator to radially expandto move a slide bar, extending through the elongate shaft and coupled toan articulation joint formed between the elongate shaft and the endeffector, laterally and thereby effect pivotal movement of the endeffector. Alternatively, delivering energy to the electroactive polymeractuator can cause the electroactive polymer actuator to axiallycontract move a slide bar, extending through the elongate shaft andcoupled to an articulation joint formed between the elongate shaft andthe end effector, laterally and thereby effect pivotal movement of theend effector. In other embodiments, energy can be delivered to a firstelectroactive polymer actuator to move the end effector in a firstdirection, and to a second electroactive polymer actuator to move theend effector in a second, opposed direction. The amount of energydelivered to the electroactive polymer actuator can correspond to adegree of movement of the end effector. In yet another embodiment,delivering energy to an electroactive polymer actuator can angularlyposition the end effector relative to the elongate shaft by flexing aflexible portion extending between the elongate shaft and the endeffector. In other embodiments, prior to simultaneously advancing aplurality of staples, tissue can be engaged between a staple applyingassembly and an anvil of the end effector. For example, energy can bedelivered to an electroactive polymer actuator to move the anvil towardthe staple applying assembly. In yet another aspect, simultaneouslyadvancing a plurality of staples can include delivering energy to anelectroactive polymer actuator coupled to a staple advancing tosimultaneously advancing a plurality of staples through the end effectorto staple tissue disposed adjacent to the end effector.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be more fully understood from the following detaileddescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1A is a cross-sectional view of a prior art fiber bundle type EAPactuator;

FIG. 1B is a radial cross-sectional view of the prior art actuator shownin FIG. 1A;

FIG. 2A is a cross-sectional view of a prior art laminate type EAPactuator having multiple EAP composite layers;

FIG. 2B is a perspective view of one of the composite layers of theprior art actuator shown in FIG. 2A;

FIG. 3A is a partially cross-sectional perspective view of one exemplaryembodiment of a circular stapler having a stapling apparatus formed on adistal end thereof with an anvil and staple applying assembly;

FIG. 3B is a cross-sectional view of a distal portion of the circularstapler of FIG. 3A showing one exemplary embodiment of an electroactivepolymer actuator assembly for actuating the staple applying assembly;

FIG. 3C is a partially cross-sectional view of another embodiment of adistal portion of a circular stapler having an electroactive polymeractuator for driving staples through a staple applying assembly;

FIG. 4A is a cross-sectional view of a distal portion of an exemplaryembodiment of a circular stapler, showing EAP actuators in anon-actuated configuration for effecting articulation of the stapleapplying assembly;

FIG. 4B is a cross-sectional view of the distal portion of the circularstapler shown in FIG. 4A, showing one of the EAP actuators electricallyactuated to articulate the staple applying assembly;

FIG. 5A is an exploded perspective view of another embodiment of astaple applying assembly movably coupled to a distal portion of anelongate shaft and having EAP actuators for articulating the stapleapplying assembly;

FIG. 5B is a partially cross-sectional view of the staple applyingassembly and elongate shaft shown in FIG. 5A, showing one of the EAPactuators electrically actuated to articulate the staple applyingassembly;

FIG. 6 is a partially cross-sectional view of another embodiment of astaple applying assembly movably coupled to a distal portion of anelongate shaft and having EAP actuators for articulating the stapleapplying assembly;

FIG. 7A is a partially cross-sectional view of another embodiment of astaple applying assembly movably coupled to a distal portion of anelongate shaft and having EAP actuators for articulating the stapleapplying assembly;

FIG. 7B is a partially cross-sectional view of the staple applyingassembly and elongate shaft shown in FIG. 7A, showing one of the EAPactuators electrically actuated to articulate the staple applyingassembly;

FIG. 8A is a partially cross-sectional view of yet another embodiment ofa staple applying assembly movably coupled to a distal portion of anelongate shaft and having EAP actuators for articulating the stapleapplying assembly;

FIG. 8B is a partially cross-sectional view of the staple applyingassembly and elongate shaft shown in FIG. 8A, showing one of the EAPactuators electrically actuated to articulate the staple applyingassembly;

FIG. 9 is a perspective view of yet another embodiment of a stapleapplying assembly movably coupled by a flexible portion to a distalportion of an elongate shaft and having EAP actuators for articulatingthe staple applying assembly;

FIG. 10 is a perspective view of yet another embodiment of a stapleapplying assembly movably coupled by a flexible portion to a distalportion of an elongate shaft and having EAP actuators for articulatingthe staple applying assembly;

FIG. 11A is a perspective view of one exemplary embodiment of a lockingmechanism in an unactivated position for locking a movable joint betweena staple applying assembly and an elongate shaft in any of FIGS. 4A-10;and

FIG. 11B is a perspective view of the locking mechanism of FIG. 11Aactivated to lock the movable joint in a fixed position.

DETAILED DESCRIPTION OF THE INVENTION

Certain exemplary embodiments will now be described to provide anoverall understanding of the principles of the structure, function,manufacture, and use of the devices and methods disclosed herein. One ormore examples of these embodiments are illustrated in the accompanyingdrawings. Those of ordinary skill in the art will understand that thedevices and methods specifically described herein and illustrated in theaccompanying drawings are non-limiting exemplary embodiments and thatthe scope of the present invention is defined solely by the claims. Thefeatures illustrated or described in connection with one exemplaryembodiment may be combined with the features of other embodiments. Suchmodifications and variations are intended to be included within thescope of the present invention.

The present invention generally provides methods and devices foreffecting movement of one or more components of a circular stapler. Inone exemplary embodiment, a circular stapler is provided having anelongate shaft with an end effector or staple applying assembly coupledthereto. An electrically expandable and contractible actuator, such asan electroactive polymer actuator, can be used to actuate the stapleapplying assembly, thereby driving one or more staples, and preferably aplurality of staples in a substantially curved pattern, into tissue. Anelectrically expandable and contractible actuator can also optionally beused to move an anvil toward a staple applying assembly. In anotherembodiment, a circular stapler is provided having a stapling apparatusthat is movably coupled to a distal end of an elongate shaft. Anelectrically expandable and contractible motor, such as an electroactivepolymer actuator, can be used to pivotally or angularly adjust aposition of the stapling apparatus relative to the elongate shaft bydelivering energy to the electroactive polymer actuator. A personskilled in the art will appreciate that the circular stapler can have avariety of configurations, and that one or more electroactive polymeractuators can be coupled to one or more components of the circularstapler to effect movement.

Electroactive Polymers

Electroactive polymers (EAPs), also referred to as artificial muscles,are materials that exhibit piezoelectric, pyroelectric, orelectrostrictive properties in response to electrical or mechanicalfields. In particular, EAPs are a set of conductive doped polymers thatchange shape when an electrical voltage is applied. The conductivepolymer can be paired to some form of ionic fluid or gel and electrodes,and the flow of ions from the fluid/gel into or out of the conductivepolymer can induce a shape change of the polymer. Typically, a voltagepotential in the range of about 1V to 4 kV can be applied depending onthe particular polymer and ionic fluid or gel used. It is important tonote that EAPs do not change volume when energized, rather they merelyexpand in one direction and contract in a transverse direction.

One of the main advantages of EAPs is the possibility to electricallycontrol and fine-tune their behavior and properties. EAPs can bedeformed repetitively by applying external voltage across the EAP, andthey can quickly recover their original configuration upon reversing thepolarity of the applied voltage. Specific polymers can be selected tocreate different kinds of moving structures, including expanding, linearmoving, and bending structures. The EAPs can also be paired tomechanical mechanisms, such as springs or flexible plates, to change theeffect that is caused when voltage is applied.

There are two basic types of EAPs and multiple configurations for eachtype. The first type is a fiber bundle that can consist of numerousfibers bundled together to work in cooperation. The fibers typicallyhave a size of about 30-50 microns. These fibers may be woven into thebundle much like textiles and they are often referred to as EAP yarn. Inuse, the mechanical configuration of the EAP determines the EAP actuatorand its capabilities for motion. For example, the EAP may be formed intolong stands and wrapped around a single central electrode. A flexibleexterior outer sheath will form the other electrode for the actuator aswell as contain the ionic fluid necessary for the function of thedevice. When voltage is applied thereto, the EAP will swell causing thestrands to contract or shorten. The fibers can alternatively beconfigured to expand or lengthen. An example of a commercially availablefiber EAP material is manufactured by Santa Fe Science and Technologyand sold as PANION™ fiber and described in U.S. Pat. No. 6,667,825,which is hereby incorporated by reference in its entirety.

FIGS. 1A-1B illustrate one exemplary embodiment of an EAP actuator 100formed from a fiber bundle. As shown, the actuator 100 generallyincludes a flexible conductive outer sheath 102 that is in the form ofan elongate cylindrical member having opposed end caps 102 a, 102 bformed thereon. The outer sheath 102 can, however, have a variety ofother shapes and sizes depending on the intended use. As is furthershown, the outer sheath 102 is coupled to an energy delivering electrode108 a and a return electrode 108 b. In the illustrated embodiment, theenergy delivering electrode 108 a extends through one of the end caps,e.g., end cap 102 a, through the inner lumen of the conductive outersheath 102, and into the opposed end cap, e.g., end cap 102 b. Theenergy delivering electrode 108 a can be, for example, a platinumcathode wire, and it can be coupled to any portion of the outer sheath102. The conductive outer sheath 102 can also include an ionic fluid orgel 106 disposed therein for transferring energy from the energydelivering electrode 108 a to the EAP fibers 104, which are disposedwithin the outer sheath 102. In particular, several EAP fibers 104 arearranged in parallel and extend between and into each end cap 102 a, 102b. As noted above, the fibers 104 can be arranged in variousorientations to provide a desired outcome, e.g., radial expansion orcontraction, or bending movement. In use, energy can be delivered to theactuator 100 through the active energy delivering electrode 106 a. Theenergy will cause the ions in the ionic fluid to enter into the EAPfibers 104, thereby causing the fibers 104 to expand in one direction,e.g., radially such that an outer diameter of each fiber 104 increases,and to contract in a transverse direction, e.g., axially such that alength of the fibers decreases. As a result, the end caps 102 a, 102 bwill be pulled toward one another, thereby contracting and decreasingthe length of the flexible outer sheath 102.

The other type of EAP is a laminate structure, which consists of one ormore layers of an EAP, a layer of ionic gel or fluid disposed betweeneach layer of EAP, and one or more flexible plates attached to thestructure. When a voltage is applied, the laminate structure expands inone direction and contracts in a transverse or perpendicular direction,thereby causing the flexible plate(s) coupled thereto to shorten orlengthen, or to bend or flex, depending on the configuration of the EAPrelative to the flexible plate(s). An example of a commerciallyavailable laminate EAP material is manufactured by Artificial MuscleInc, a division of SRI Laboratories. Plate EAP material, referred to asthin film EAP, is also available from EAMEX of Japan.

FIGS. 2A-2B illustrate an exemplary configuration of an EAP actuator 200formed from a laminate. Referring first to FIG. 2A, the actuator 200 caninclude multiple layers, e.g., five layers 210, 210 a, 210 b, 210 c, 210d are shown, of a laminate EAP composite that are affixed to one anotherby adhesive layers 103 a, 103 b, 103 c, 103 d disposed therebetween. Oneof the layers, i.e., layer 210, is shown in more detail in FIG. 2B, andas shown the layer 210 includes a first flexible conductive plate 212 a,an EAP layer 214, an ionic gel layer 216, and a second flexibleconductive plate 212 b, all of which are attached to one another to forma laminate composite. The composite can also include an energydelivering electrode 218 a and a return electrode 218 b coupled to theflexible conductive plates 212 a, 212 b, as further shown in FIG. 2B. Inuse, energy can be delivered to the actuator 200 through the activeenergy delivering electrode 218 a. The energy will cause the ions in theionic gel layer 216 to enter into the EAP layer 214, thereby causing thelayer 214 to expand in one direction and to contract in a transversedirection. As a result, the flexible plates 212 a, 212 b will be forcedto flex or bend, or to otherwise change shape with the EAP layer 214.

Circular Stapler

As previously indicated, in an exemplary embodiment circular staplingmethods and devices are provided that utilize electrically expandableand contractible actuators, such as EAP actuators, to effectarticulation and/or actuation of various components of the device. Thevarious methods and devices disclosed herein for effecting articulationand actuation can be incorporated into virtually any circular staplerknown in the art, and the circular stapler can include a variety ofother features known in the art and not disclosed herein. FIGS. 3A-3Cillustrate exemplary circular staplers that can include one or more EAPactuators for effecting articulation and/or actuation. A person skilledin the art will appreciate that, while the various embodiments aredescribed as having EAP actuators for affecting articulation and/oractuation without mechanical assistance, the actuators can alternativelybe configured to supplement mechanical articulation and/or actuation.

In general, the stapler 10 includes an elongate shaft 12 having a handle14 coupled to a proximal end 12 a thereof, and a stapling apparatus 11coupled to the distal end 12 b thereof. The stapling apparatus 11includes a staple applying assembly 16 and an anvil 18 that are adaptedto receive tissue therebetween. The staple applying assembly 16 isadapted to contain a staple cartridge 44 having multiple staplesdisposed therein and configured to be driven into tissue by a plunger ordriver 42, and the anvil 18 is adapted to deform the staples. In use,tissue is positioned between the anvil 18 and the staple applyingassembly 16, and the anvil 18 is then moved from an open position to aclosed position to engage the tissue between the anvil 18 and the stapleapplying assembly 16. The stapling apparatus 11 can optionally bepivoted relative to the elongate shaft 12 to facilitate positioning ofthe tissue therein. Once the tissue is engaged between the anvil 18 andthe staple applying assembly 16, the staple applying assembly 16 isactuated to drive one or more staples through the tissue and against theanvil 18, which deforms the legs of the staple. In an exemplaryembodiment, multiple staples are applied to the tissue in asubstantially circular pattern. The circular stapler 10 is particularlysuitable for endoscopic and laparoscopic procedures, as the relativelysmall diameter of the elongate shaft 12 allows it to fit through smallaccess ports or pathways. The stapler, however, can be adapted for usein a variety of medical procedures.

In order to articulate the stapling apparatus (i.e., angularly positionthe stapling apparatus) relative to the elongate shaft 12, close theanvil 18, and/or actuate (fire) the staple applying assembly 16, thedevice 10 can include a trigger, rotatable knob, handle, switch, orother mechanism formed on the handle 14. In an exemplary embodiment, asshown in FIG. 3A, the handle 14 includes a first switch 13 formedthereon for closing the stapling apparatus 11, i.e., for moving theanvil 18 toward the staple applying assembly 16. The handle 14 can alsoinclude a second switch 15 coupled thereto for firing the staplecartridge 44 in the staple applying assembly 16 to deliver one or morestaples or clips into tissue. The second switch 15 can also be effectiveto advance a blade distally through the staple applying assembly 16 tocut stapled tissue. A person skilled in the art will appreciate thatwhile switches 13, 15 are shown, a trigger, rotatable knob, lever,sliding knob, or other mechanism can be used for articulating thestapling apparatus 11 relative to the elongate shaft 16, moving theanvil 18 toward the staple applying assembly 16, and/or actuating thestaple applying assembly 16.

Actuation

As indicated above, the present invention provides exemplary methods anddevices for actuating a stapling apparatus on a circular stapler,including firing the staples and optionally driving a knife or bladethrough the staple applying assembly to cut the stapled tissue. FIG. 3Billustrates a portion of the circular stapler 10 of FIG. 3A in moredetail, showing one exemplary embodiment of a technique for firing thestaple applying assembly 16 and/or for driving a blade through thestaple applying assembly 16 to cut stapled tissue using one or more EAPactuators. A person skilled in the art will appreciate that the staplingapparatus can have a variety of configurations, and that EAP actuatorscan be incorporated into a variety of other staple applying assembliesto effect firing and/or cutting.

As shown, the elongate shaft 12 includes a plunger 42 a disposed thereinand adapted to move between a proximal position and a distal position.The plunger 42 a can form the staple driver, or it can be coupled to astaple driver 42 b, as shown, to advance the staple driver 42 bdistally, thereby driving staples through the staple applying assembly16 and toward the anvil 18 and/or to cut tissue engaged by the staplingapparatus 11. As is further shown in FIG. 3B, the plunger 42 a iscoupled to multiple EAP actuator cords that are effective to move theplunger 42 a longitudinally between the proximal and distal positions.In particular, the proximal end of the plunger 42 a can include a discor flange 49 formed therearound, and multiple EAP actuator cords 60 canbe coupled to the flange 49 to move the plunger 42 a relative to theelongate shaft 12. In the illustrated embodiment, the elongate shaft 12includes a ground disc 47, which can function as a ground for the EAPactuator cords 60, fixedly coupled to the inner sidewalls thereof. Theground disc 47 is positioned distal of the flange 49 formed on theplunger 42 a, and multiple EAP actuator cords 60 extend between theground disc 47 and the flange 49. When energy is delivered to the EAPactuator cords 60, the cords 60 will axially contract or shorten,thereby pulling the flange 49 and the plunger 42 a in a distal directiontoward the ground disc 47. As a result, the plunger 42 a will advancedistally, pushing the staple driver 42 b distally to drive staplesthrough the staple cartridge in the staple applying assembly 16. Energydelivery can be terminated to axially expand and return the actuatorcords 60 to their initial position, thereby moving the plunger 42 aproximally. The plunger 42 a can also or alternatively be coupled to aknife driver 43 that is effective to drive a blade 41 distally to cuttissue. In other embodiments, a separate electroactive polymer actuatorassembly could be coupled to the knife driver 43 to allow the blade tobe driven separate from the staple driver 42 b. A person skilled in theart will appreciate that various drivers and/or cutting blades known inthe art can be used with the stapling apparatus 11, and that one or moreelectroactive polymer actuators can be coupled to the driver and/orcutting blade in a variety of configurations to actuate the driverand/or cutting blade.

FIG. 3C illustrates another embodiment of a technique for actuating astaple applying assembly of a circular stapler. In this embodiment,rather than pulling the plunger or driver distally using electroactivepolymer actuators that axially contract, the plunger or driver can bepushed axially to drive staples through the staple applying assembly. Inparticular, FIG. 3C illustrates a distal portion of an elongate shaft 82of a circular stapler. A driver 84 is slidably disposed within theelongate shaft 82 and it is adapted to move between a proximal positionand a distal position, in which the driver 84 drives staples through astaple cartridge 86 disposed within the staple applying assembly 88 andtoward an anvil 98, which deforms the staples. An electroactive polymeractuator 94 is disposed between a proximal portion 84 a of the driver 84and distal portion 84 b of the driver. This can be achieved, forexample, using a laminate or composite type electroactive polymeractuator that is adhered to a terminal end of each of the proximal anddistal portions 84 a, 84 b to connect the portions. In use, energy canbe delivered to the electroactive polymer actuator 94 through electrodesthat are coupled to a power source that is disposed within the handle ofthe device or that is mated to the handle of the device. The energy willcause the electroactive polymer actuator to axially expand, therebypushing the distal portion 84 b of the driver 84 toward the stapleapplying assembly 88 to drive staples through the staple cartridge 86and toward the anvil 98. Termination of energy delivery will cause theelectroactive polymer actuator to axially contract, thereby pulling thedistal portion 84 b of the driver proximally to its initial position. Aperson skilled in the art will appreciate that a variety of othertechniques can be used to move a driver or plunger of a circular staplerusing electroactive polymer actuators.

Articulation

As previously indicated, the present invention also provides exemplarymethods and devices for articulating a stapling apparatus of a circularstapler. FIGS. 4A-11B illustrate various exemplary embodiments ofarticulation joints and electroactive polymer actuators for effectingarticulation.

Referring first to FIGS. 4A-4B, a distal end 612 b of the elongate shaft612 is shown coupled to a proximal end of the stapling apparatus 611 bya pivot joint 616, such that the stapling apparatus 611 can pivotrelative to the shaft 612 about the pivot joint 616. The device alsoincludes a slide bar 624 extending through the elongate shaft 612 andhaving a distal end 624 d with gear teeth 624 t formed thereon andadapted to engage corresponding gear teeth 616 t formed on the staplingapparatus 611. The device can also include one or more electricallyexpandable and contractible actuators, such as an EAP actuator, formoving the slide bar 624 to cause the gear teeth 624 t on the slide bar624 to move the gear teeth 624 t on the stapling apparatus 611 andthereby pivot the stapling apparatus 611 relative to the elongate shaft612. While the EAP actuator(s) can effect movement of the slide bar 624using a variety of techniques, in one exemplary embodiment the EAPactuators are configured to move the slide bar 624 laterally. Inparticular, a first EAP actuator 626 a can extend through at least aportion of the elongate shaft 612 adjacent to a first lateral side ofthe slide bar 624, and a second EAP actuator 626 b can extend through atleast a portion of the elongate shaft 612 adjacent to a second, opposedlateral side of the slide bar 624, as shown in FIGS. 4A-4B. Either typeof EAP actuator can be used, but in an exemplary embodiment the EAPactuators 626 a, 626 b are laminate type EAP actuators that are adaptedto expand laterally when energy is delivered thereto. FIG. 4Aillustrates both actuators 626 a, 626 b in a non-expanded, un-actuatedconfiguration, where no energy is delivered to either actuator 626 a,626 b. FIG. 4B illustrates the first EAP actuator 626 a laterallyexpanded to move the slide bar 624 laterally toward the second EAPactuator 626 b, thereby causing the slide bar 624 to pivot the staplingapparatus 611 in a direction opposite to the direction of movement ofthe slide bar 624. Energy can be delivered to the actuators 626 a, 626 bthrough electrodes extending through the shaft 612 and coupled to anenergy source disposed within or coupled to a handle of the device,e.g., a battery source or an electrical outlet or other energy source.The handle can also include a control mechanism, such as a slidinglever, rotatable knob, or dial, coupled thereto and adapted to controlthe amount of energy delivered to each actuator 626 a, 626 b. The amountof energy delivered to each actuator 626 a, 626 b is determinative ofthe amount of expansion of the actuators 626 a, 626 b, thus allowing theamount of pivotal movement of the stapling apparatus 611 to beselectively adjusted.

A person skilled in the art will appreciate that, while FIGS. 4A-4Billustrate a laterally-moving slide bar 624 with laterally expanding EAPactuators 626 a, 626 b, the slide bar 624 and actuators 626 a, 626 b canhave a variety of other configurations. For example, multiple EAPactuators in the form fiber bundles can extend laterally between aninner surface of the elongate shaft 612 and the slide bar 624. Whenenergy is delivered to the actuators, the actuators can contract orshorten in length to pull the slide bar 624 toward the elongate shaft612, thereby moving the slide bar 624 laterally. Alternatively, theslide bar 624 can be configured to move longitudinally to effectmovement of the stapling apparatus 611, and the EAP actuator can be usedto effect longitudinal movement of the slide bar 624. In otherembodiments, the slide bar itself, or at least a portion of the slidebar, can be formed from an EAP actuator that is adapted to expandaxially in a desired direction to move the slide bar laterally.

FIGS. 5A-5B illustrate another embodiment of a technique forarticulating a circular stapler. In this embodiment, the staplingapparatus 711 is pivotally coupled to the elongate shaft 712 by firstand second opposed arms 790 a, 790 b coupled to opposed sides of theelongate shaft 712. First and third EAP actuators 726 a, 726 c areattached to and extend from opposed sides of a terminal end of the firstarm 790 a, and second and fourth EAP actuators 726 b, 726 d are attachedto and extend from opposed sides of a terminal end of the second arm 790b. The distal end of each EAP actuator 726 a-d is coupled to an innersidewall of the elongate shaft 712 at an attachment point (first,second, and third attachment points 792 a, 792 b, 792 c are shown). As aresult, the first and second actuators 726 a and 726 b are attached toone side of the elongate shaft 712, and the third and fourth actuators726 c and 726 d are attached to an opposite side of the elongate shaft712. In use, energy can be delivered to the first and second EAPactuators 726 a, 726 b to cause the actuators 726 a, 726 b to axiallycontract or shorten, thereby pulling the first and second arms 790 a,790 b in a lateral direction towards the first and second attachmentpoints 792 a, 792 b. As a result, the stapling apparatus 711 is pivotedin a first direction. When energy delivery is terminated, the first andsecond actuators 726 a, 726 b will axially expand returning to theirinitial configuration, thereby moving the stapling apparatus 711 to itsinitial position in which it is longitudinally aligned with the elongateshaft 712. Energy can be delivered to the third and fourth actuators 726c, 726 d to similarly move the stapling apparatus 711 in an oppositedirection. As previously discussed, the amount of energy delivered canbe controlled to control the amount of pivotal movement of the staplingapparatus 711. As shown in FIG. 5B, the device can also include acovering 799 surrounding at least a portion of the pivot frame assembly757 to provide support thereto.

FIG. 6 illustrates yet another embodiment of a technique forarticulating a circular stapler. In this embodiment, one or moreactuating members can be incorporated into a pulley 898 that is part ofa pivoting frame assembly 857. The pulley 898 can be made entirely ofEAP actuators or, alternatively, EAP actuators can be attached toproximal and distal ends of the pulley 898. In the illustratedembodiment, first and second EAP actuators 826 a, 826 b are attached tothe proximal and distal ends of the pulley 898. The EAP actuators 826 a,826 b are anchored to the elongate shaft 812 to push and pull thestapling apparatus 811 to effect articulation. In particular, energydelivery to one of the EAP actuators, e.g., the first EAP actuator 826a, causes the first EAP actuator 826 a to axially contract or shorten tomove the pulley 898 in a first direction, thereby causing the staplingapparatus 811 to pivot in a first direction. Conversely, energy deliveryto the second EAP actuator 826 b causes the second EAP actuator toaxially contract or shorten to move the pulley 898 in a second, oppositedirection, thereby causing the stapling apparatus 811 to pivot in asecond, opposite direction. Again, energy delivery can be controlled tocontrol the amount of movement of the stapling apparatus 811.

FIGS. 7A-7B illustrate another embodiment of a technique forarticulating a stapling apparatus relative to an elongate shaft of acircular stapler. In this embodiment, the elongate shaft 912 includes aslide bar 924 extending therethrough and having a ball 924 t formed on adistal end thereof and received within a corresponding socket 916 sformed in a proximal end of the stapling apparatus 911. The slide bar924 also includes cam surfaces 925 a, 925 b formed thereon, preferablyat a location proximal to the distal end of the elongate shaft 912. Thecam surfaces 925 a, 925 b can have a variety of shapes and sizes, but inan exemplary embodiment, as shown, the cam surfaces 925 a, 925 b extendoutward from opposed sides of the slide bar 924 and they arewedge-shaped members that increase in width in a proximal-to-distaldirection. The device also includes first and second actuating members926 a, 926 b extending through the elongate shaft 912 and positioned onopposed sides of the slide bar 924. Each actuating member 926 a, 926 bincludes a cam surface 927 a, 927 b formed thereon and adapted to abutagainst the cam surfaces 925 a, 925 b formed on the slide bar 924. As aresult, distal movement of the first actuating member 926 a will causethe cam surface 927 a formed thereon to slide against the cam surface925 a formed on the slide bar 924, thereby moving the slide bar 924laterally away from the first actuating member 926 a. As a result of thelateral movement of the slide bar 924, the ball 924 t will cause thestapling apparatus 911 to pivot relative to the elongate shaft 912.Conversely, distal movement of the second actuating member 926 b willcause the cam surface 927 b formed thereon to slide against the camsurface 925 b formed on the slide bar 924, thereby moving the slide bar924 laterally away from the second actuating member 926 b, and thuspivoting the stapling apparatus 911 in an opposite direction. A biasingelement (not shown), such as a spring, can be disposed on each side ofthe slide bar 924 to bias the slide bar 924 to the central, restingposition shown in FIG. 7A, thereby allowing the slide bar 924 to returnto the resting position when the actuating member 926 a, 926 b is movingproximally.

In an exemplary embodiment, movement of each actuating member 926 a, 926b can be achieved using an EAP actuator coupled thereto. As shown inFIGS. 7A-7B, an EAP actuator cord 928 a, 928 b, preferably in the formof a fiber bundle type actuator, extends between a distal end of eachactuating member 926 a, 926 b and a distal end of the shaft 912. Whenenergy is selectively delivered to one of the EAP actuating cords, e.g.,the first actuating cord 928 a, the cord 928 a will axially contract orshorten, as shown in FIG. 7B, thereby pulling the actuating member 926 acoupled to the actuated EAP cord 928 a in a distal direction. The camsurface 927 a on the actuating member 926 a will abut against the camsurface 925 a on the slide bar 924 to move the slide bar 924 laterallytoward the second actuating member 926 b. As a result, the ball 924 t onthe distal end of the slide bar 924 will cause the stapling apparatus911 to articulate or pivot thereabout.

A person skilled in the art will appreciate that the EAP actuators canhave a variety of other configurations, and they can effect movement ofthe slide bar using a variety of other techniques. For example, ratherthan pulling the slide bar 924 distally when energy is delivered to theEAP actuating cords 928 a, 928 b, the EAP actuators can be coupled to aproximal end of the slide bar 924 and they can be adapted to push theslide bar 924 distally. In other embodiments, the cam surface 927 a, 927b formed on each actuating member 926 a, 926 b can be formed from an EAPactuator such that energy delivery to the cam surface 927 a, 927 bcauses the cam surface 927 a, 927 b to expand toward the slide bar 924,thereby moving the slide bar 924 in a desired direction to articulatethe stapling apparatus 911. The amount of movement of each actuatingmember 926 a, 926 b, and thus the amount of articulation of the staplingapparatus 911, can also be controlled by controlling the amount ofenergy delivered to each EAP actuator.

FIGS. 8A-8B illustrate yet another embodiment of a technique forarticulating a stapling apparatus of a circular stapler. In thisembodiment, rather than using a slide bar to pivot the staplingapparatus, two actuating members 26 a, 26 b are coupled directly toopposed sides of the stapling apparatus 412 to push and pull thestapling apparatus 412 to effect articulation. In particular, a distalend of each actuating member 26 a, 26 b is coupled to a proximal end ofthe stapling apparatus 412 by a pivot joint, such that proximal movementof the first actuating member 26 a causes the stapling apparatus 412 topivot about the second actuating member 26 b, and proximal movement ofthe second actuating member 26 b causes the stapling apparatus 412 topivot about the first actuating member 26 a. The actuating members 26 a,26 b can be moved using a variety of techniques. For example, all or aportion of each actuating member 26 a, 26 b can be formed from an EAPthat is adapted to axially expand, or the actuating members 26 a, 26 bcan be coupled to an EAP actuator for moving the actuating members 26 a,26 b proximally and distally to articulate the stapling apparatus 412.

FIG. 9 illustrates another embodiment of a technique for articulating astapling apparatus of a circular stapler. In this embodiment, theelongate shaft 20 includes a flexible portion formed by a plurality ofcut out portions 22, 24, 26, 28, 30, 32, 34, 36, 38, 40 (hereinafter22-40) formed on opposed sides of the elongate shaft 20. The cut outportions allow the elongate shaft 20 to flex thereabout. One or moreactuators can be positioned relative to the cut out portions to effectpivotal or bending movement of a stapling apparatus (not shown) relativeto the elongate shaft 20. FIG. 9 illustrates multiple EAP actuator cords46, 48, 50, 52, 54, 56, 58 (hereinafter 46-58) extending longitudinallythrough the elongate shaft 20 where the cut out portions are formed. TheEAP actuator cords 46-58 extend longitudinally parallel to one another,and they are coupled to the elongate shaft 20 at a first end justproximal to the cut out portions 22-40 and at a second end just distalto the cut out portions 22-40. In use, energy can be selectivelydelivered to any one or combination of the EAP actuator cords 46-58 toflex the cut out portions 22-40 and thereby articulate the staplingapparatus in a desired direction. For example, energy can be deliveredto the first EAP actuator cord 46 to cause the first actuator cord 46 toaxially contract or shorten, thereby pulling the opposed ends of thecord 46 toward one another. Since the ends of the first actuator cord 46are attached to the elongate shaft 20 at opposed ends of the cut outportions, and since the first EAP actuator cord 46 is offset from acentral axis of the elongate shaft 20, the first EAP actuator cord 46will cause the elongate shaft 20 to bend in a first direction.Accordingly, one or more actuator cords 46-58 can be selectivelyactivated, i.e., energy can be selectively delivered thereto, to effectmovement of the stapling apparatus in a desired direction. A personskilled in the art will appreciate that a variety of other techniquescan be used to cause the cut out portions to bend.

FIG. 10 illustrates yet another embodiment of a technique forarticulating a stapling apparatus using a flexible portion 12 p′″ formedbetween the stapling apparatus and the elongate shaft 12′″. In thisembodiment, one or more EAP actuators can be positioned within, on, oraround the flexible portion 12 p′″ of the elongate shaft 12′″ at variouslocations, and the EAP actuators can be configured to flex the flexibleportion 12 p′″ when energy is delivered to the actuators, therebyarticulating the stapling apparatus. FIG. 10 illustrates multiple EAPactuators 26 ₁, 26 ₂, 26 ₃, 26 ₄, 26 ₅ extending axially along distinctportions of the flexible portion 12 p′″ of the elongate shaft 12′″.While not shown, multiple EAP actuators can be positioned at variousother locations around the circumference of the flexible portion 12 p′″.In use, energy delivery to the first actuator 26 ₁, for example, cancause the first actuator 26 ₁ to axially contract thereby bending aportion of the flexible portion 12 p′″. A user can thus selectivelydeliver energy to one or more actuators to articulate and position thestapling apparatus as desired.

A person skilled in the art will appreciate that any of the aboveembodiments can include a locking feature that allows the device tomaintain its articulated position when energy delivery is terminated tothe EAP actuators. In particular, when energy delivery is terminated theEAP actuator(s) axially expands to return the stapling apparatus to itsinitial position in which it is longitudinally aligned with the elongateshaft. A locking mechanism can thus be used to lock the staplingapparatus in a desired articulated position prior to terminating energydelivery to the EAP actuators.

While the locking mechanism can have a variety of configurations, FIGS.11A-11B illustrate one exemplary embodiment of an articulation lock 70that is incorporated into a pivoting articulation joint 62. As shown,the articulation joint 62 includes a rotary structure 72 having aplurality of holes 64 a, 64 b, 64 c, 64 d, 64 e that are adapted toreceive a plunger to prevent rotational movement of the articulationjoint 62. A stop, which in one embodiment can be a spring loaded plunger66, is formed within the elongate shaft 61 of the device and locatedproximal to the rotary structure 72. The plunger 66 is also coupled toan EAP actuator (not shown) that, when actuated with energy, effectsmovement of the plunger 66 thereby allowing the articulation joint 62 tomove. In particular, as shown in FIG. 11A, when the device is in anun-actuated position, the plunger 66 rests in one of the holes (hole 64e as shown) of the rotary structure 72, thereby maintaining the staplingapparatus in a fixed position. Energy delivery to the EAP actuator, asshown in FIG. 11B, will pull the plunger 66 out of the hole 64 e toallow the articulation joint 62 to move to a desired position. Thevarious techniques previously described can be used to articulate thestapling apparatus. Once the stapling apparatus is moved to a desiredarticulated position, the EAP actuator can be de-actuated, i.e., energydelivery can be terminated, allowing the spring to bias the plunger 66into one of the holes of the rotary structure 72. The stapling apparatusis thereby again maintained in a fixed position. One skilled in the artwill appreciate that a variety of other locking mechanisms can beincorporated into an articulating joint, such as a ratchet and teethsystem.

One skilled in the art will appreciate further features and advantagesof the invention based on the above-described embodiments. Accordingly,the invention is not to be limited by what has been particularly shownand described, except as indicated by the appended claims. Allpublications and references cited herein are expressly incorporatedherein by reference in their entirety.

1. A circular stapling device, comprising: an elongate shaft havingproximal and distal ends; a staple applying assembly coupled to thedistal end of the elongate shaft and adapted to deliver staples intotissue in a substantially curved pattern; an anvil coupled to the stapleapplying assembly and movable between an open tissue-receiving positionand a closed staple-applying position; and an electroactive polymeractuator coupled to the staple applying assembly and adapted to driveone or more staples from the staple applying assembly into tissuepositioned between the staple applying assembly and the anvil.
 2. Thedevice of claim 1, further comprising a driver disposed within thestaple applying assembly and adapted to move distally to drive staplesthrough the staple applying assembly toward the anvil, the electroactivepolymer actuator being coupled to the driver and adapted to move thedriver distally when energy is delivered to the electroactive polymeractuator.
 3. The device of claim 2, wherein the driver includes a bladeformed thereon and adapted to cut tissue being stapled.
 4. The device ofclaim 2, wherein the electroactive polymer actuator includes a first endcoupled to a portion of the staple applying assembly, and a second endcoupled to the driver.
 5. The device of claim 4, wherein the first endis positioned distal of the second end of the electroactive polymer. 6.The device of claim 5, wherein the electroactive polymer actuatorcomprises at least one electroactive polymer cord that is adapted toaxially contract when energy is delivered thereto to pull the driverdistally.
 7. The device of claim 1, further comprising a handle formedon the proximal end of the elongate shaft and including a controlmechanism adapted to selectively deliver energy to the electroactivepolymer actuator.
 8. The device of claim 1, further comprising a secondelectroactive polymer actuator coupled to the anvil and adapted to movethe anvil from the open tissue-receiving position to the closedstaple-applying position when energy is delivered to the secondelectroactive polymer actuator.
 9. The device of claim 1, wherein thestaple applying assembly is angularly adjustable relative to the distalend of the elongate shaft, and wherein the device further includes asecond electroactive polymer actuator coupled between the stapleapplying assembly and the elongate shaft and adapted to angularly adjusta position of the staple applying assembly relative to the elongateshaft when energy is delivered to the second electroactive polymeractuator.
 10. A method for stapling tissue, comprising: inserting acircular stapler into a lumen; positioning tissue to be stapled betweenan anvil and a staple applying assembly located on a distal end of thecircular stapler; and delivering energy to an electroactive polymeractuator coupled to the staple applying assembly to drive a plurality ofstaples through the staple applying assembly and against the anvil tostaple the tissue positioned therebetween with staples positioned in asubstantially curved pattern.
 11. The method of claim 10, whereindelivering energy to the electroactive polymer actuator is effective tomove a driver disposed within the staple applying assembly to drivestaples therethrough and against the anvil.
 12. The method of claim 11,wherein the electroactive polymer actuator axially contracts when energyis delivered thereto to pull the driver through the staple applyingassembly.
 13. The method of claim 10, wherein positioning tissue to bestapled between the anvil and the staple applying assembly comprisesdrawing the tissue into a gap formed between the anvil and the stapleapplying assembly, and moving the anvil toward the staple applyingassembly to engage the tissue therebetween.
 14. The method of claim 13,wherein moving the anvil toward the staple applying assembly comprisesdelivering energy to a second electroactive polymer actuator coupled tothe anvil to cause the electroactive polymer actuator to pull the anviltoward the staple applying assembly.
 15. The method of claim 10, furthercomprising cutting away a portion of stapled tissue.
 16. The method ofclaim 10, further comprising, prior to positioning tissue, angularlyadjusting a position of the staple applying assembly and the anvil. 17.The method of claim 16, wherein the staple applying assembly and theanvil are angularly adjusted by delivering energy to a secondelectroactive polymer actuator that is coupled to the staple applyingassembly.